Variable displacement swash plate type compressor

ABSTRACT

Provided is a compressor, in which the inclination angle of a swash plate is changed by an actuator, ensuring stability on a product-by-product basis while realizing reduction in size. In the compressor, when pressure in a control pressure chamber increases, a movable body moves toward a flange. At this time, the movable body pulls the opposite end side of a swash plate rearward in a swash plate chamber via first and second pulling arms. A link mechanism permits increase of the inclination angle of the swash plate until reaching a maximum value. When the pressure in the control pressure chamber reaches a required control pressure, a rear wall of the movable body which has moved rearward in the swash plate chamber abuts a front face of the flange. This makes it possible in this compressor to restrict the maximum value of the inclination angle of the swash plate.

TECHNICAL FIELD

The present invention relates to a variable displacement swash plate type compressor.

BACKGROUND ART

A conventional variable displacement swash plate type compressor (hereinafter referred to as a compressor) is disclosed in Patent Literature 1. This compressor includes a suction chamber, a discharge chamber, a swash plate chamber, and plural cylinder bores, which are formed in a housing. A drive shaft is rotatably supported in the housing. The swash plate chamber accommodates a swash plate, which is rotatable along with rotation of the drive shaft. A link mechanism is provided between the drive shaft and swash plate. The link mechanism permits change of the inclination angle of the swash plate. The inclination angle is defined as an angle of the swash plate with respect to a direction perpendicular to the drive axis of the drive shaft. A piston is reciprocally accommodated in each of the cylinder bores. A pair of shoes provided for each piston serves as a conversion mechanism and reciprocates the piston in each of the cylinder bores along with rotation of the swash plate at a stroke corresponding to the inclination angle. An actuator is capable of changing the inclination angle by changing the volume of a control pressure chamber. The actuator is controlled by a control mechanism.

In this compressor, the control mechanism raises the pressure in the control pressure chamber by using the pressure of refrigerant in the discharge chamber and thereby increases the inclination angle of the swash plate via the link mechanism. At this time, when the link mechanism is pushed by the swash plate due to the pressure in the control pressure chamber and when the length of the link mechanism in an axial direction of the drive shaft is minimized, the inclination angle cannot be increased any further. In other words, in this compressor, the maximum inclination angle is restricted by pushing the link mechanism by the swash plate. In this way, in this compressor, discharge capacity per rotation of the drive shaft can be increased to the maximum.

CITATION LIST Patent Literature

-   Patent Literature 1: Japanese Patent Laid-Open No. 5-172052

SUMMARY OF INVENTION Technical Problem

In a compressor in which the inclination angle of the swash plate is changed by an actuator as described above, a required control pressure, which is the pressure in the control pressure chamber required to increase the inclination angle of the swash plate to the maximum value, is preset. If the compressor is configured such that a discharge refrigerant pressure, i.e. the pressure of refrigerant in the discharge chamber, is introduced to the control pressure chamber, the required control pressure is set lower than an upper limit of the discharge refrigerant pressure.

In the conventional compressor described above, since the maximum value of the inclination angle is restricted by pushing the link mechanism by the swash plate, a pressure in excess of the required control pressure is applied to the swash plate and the link mechanism. This makes it necessary to secure strength of the swash plate and the link mechanism of the compressor sufficiently to endure this pressure, and, as a result, it is inevitable to increase the size of the swash plate chamber and thus the size of the compressor.

Furthermore, in the conventional compressor described above, since the maximum value of the inclination angle is restricted by the link mechanism, which is formed by assembling plural parts in the axial direction of the drive shaft, dispersion in the maximum value of the inclination angle is likely to occur due to dimensional tolerance and the like of the swash plate and the link mechanism in the axial direction of the drive shaft. Thus, it is difficult to maintain the quality of each individual compressor.

The present invention has been made in view of the conventional circumstances described above, and an object of the invention is to provide a compressor, in which the inclination angle of a swash plate is changed by an actuator, ensuring excellent quality stability on a product-by-product basis while realizing reduction in size.

Solution to Problem

A variable displacement swash plate type compressor according to the present invention comprises: a housing in which a suction chamber, a discharge chamber, a swash plate chamber, and a cylinder bore are formed; a drive shaft extending along a drive axis and rotatably supported in the housing; a swash plate rotatable in the swash plate chamber along with rotation of the drive shaft; a link mechanism that is provided between the drive shaft and the swash plate and permits change of an inclination angle of the swash plate in a direction perpendicular to the drive axis of the drive shaft; a piston reciprocally accommodated in the cylinder bore; a conversion mechanism that reciprocates the piston in the cylinder bore along with rotation of the swash plate at a stroke corresponding to the inclination angle; an actuator capable of changing the inclination angle; and a control mechanism that controls the actuator,

wherein the suction chamber and the swash plate chamber communicate with each other,

the actuator includes a partition body provided on the drive shaft, a movable body that is movable along the drive axis of the drive shaft in the swash plate chamber and provided with a coupling portion to be coupled to the swash plate, and a control pressure chamber that is defined by the partition body and the movable body and moves the movable body by introducing a refrigerant from the discharge chamber, and

a maximum inclination restriction member that rotates synchronously with the drive shaft and restricts a maximum value of the inclination angle by abutting the movable body is provided on the drive shaft.

In the compressor according to the present invention, the required control pressure is also set lower than the upper limit of the discharge refrigerant pressure. In this compressor, the movable body of the actuator moves when the refrigerant is introduced into the control pressure chamber from the discharge chamber. Thereby, the inclination angle of the swash plate changes in this compressor. In the compressor, the maximum value of the inclination angle of the swash plate is restricted as the movable body abuts the maximum inclination restriction member. That is, in this compressor, although the movable body and the swash plate are coupled to each other via the coupling portion, the swash plate does not push the link mechanism using the pressure in the control pressure chamber in order to restrict the maximum value of the inclination angle. Consequently, in this compressor, pressure in excess of the required control pressure does not act on the swash plate and the link mechanism, and therefore, it is not necessary to ensure the strength of the swash plate and the link mechanism more than required. Thus, the compressor eliminates the need to upsize the swash plate chamber.

Also, in the compressor, the maximum value of the inclination angle is restricted by having the movable body abut the maximum inclination restriction member rather than by use of the link mechanism. Consequently, even if the swash plate and the link mechanism have dimensional tolerance and the like in the axial direction of the drive shaft, such tolerance does not cause dispersion in the maximum value of the inclination angle.

Furthermore, since the maximum inclination restriction member rotates synchronously with the drive shaft, even when the movable body abuts the maximum inclination restriction member, rotation of the movable body and the swash plate is not restricted by the maximum inclination restriction member.

Thus, the compressor according to the present invention, in which the inclination angle of the swash plate is changed by the actuator, ensures excellent quality stability on a product-by-product basis while realizing reduction in size.

In the compressor according to the present invention, various members may be employed as the maximum inclination restriction member as long as the members have sufficient strength to endure pressure in excess of the required control pressure and are rotatable synchronously with the drive shaft. Furthermore, for example, a protrusion or the like may be formed on the movable body exclusively for the purpose of abutting the maximum inclination restriction member.

In the compressor according to the present invention, the drive shaft may include a drive shaft body and a cap that is press-fitted to the drive shaft body and located in the swash plate chamber. It is preferable that the cap is the maximum inclination restriction member. In this case, by having the movable body abut the cap, it is possible to restrict the maximum value of the inclination angle. Furthermore, when the cap is the maximum inclination restriction member, it is possible to adjust a position where the movable body abuts the cap depending on the shape of the cap and the position where the cap is press-fitted to the drive shaft body. Thus, the compressor is able to suitably restrict the maximum value of the inclination angle.

The compressor according to the present invention may comprise a circlip that is fitted to the drive shaft and located in the swash plate chamber. It is also preferable that the circlip is the maximum inclination restriction member. Also in this case, it is possible to adjust a position where the movable body abuts the circlip depending on the position where the circlip is fitted to the drive shaft body. Thus, this compressor is also able to suitably restrict the maximum value of the inclination angle.

Advantageous Effects of Invention

The compressor according to the present invention, in which the inclination angle of the swash plate is changed by the actuator, ensures excellent quality stability on a product-by-product basis while realizing reduction in size.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view of a compressor according to Embodiment 1 at the time of maximum displacement.

FIG. 2 is a schematic diagram showing a control mechanism of the compressor according to Embodiment 1.

FIG. 3 is a perspective view showing a movable body of the compressor according to Embodiment 1 when viewed from the front.

FIG. 4 is a sectional view of the compressor according to Embodiment 1 at the time of minimum displacement.

FIG. 5 is an enlarged sectional view showing principal part of a compressor according to Embodiment 2 at the time of maximum displacement.

DESCRIPTION OF EMBODIMENTS

Embodiments 1 and 2, which embody the present invention, will be described below with reference to the drawings. The compressors according to Embodiments 1 and 2 are variable displacement double head swash plate type compressors. These compressors are both mounted on vehicles and constitute refrigeration circuits of vehicle air-conditioning apparatus.

Embodiment 1

As shown in FIG. 1, a compressor according to Embodiment 1 comprises a housing 1, a drive shaft 3, a swash plate 5, a link mechanism 7, plural pistons 9, a pair of shoes 11 a and 11 b, and an actuator 13 as well as a control mechanism 15 which is shown in FIG. 2.

As shown in FIG. 1, the housing 1 includes a front housing 17 located at a front position in the compressor, a rear housing 19 located at a rear position in the compressor, first and second cylinder blocks 21 and 23 located between the front housing 17 and the rear housing 19, and first and second valve forming plates 39 and 41.

A boss 17 a, which protrudes frontward, is formed in the front housing 17. A shaft seal device 25 is provided in the boss 17 a. A first suction chamber 27 a and a first discharge chamber 29 a are formed in the front housing 17. The first suction chamber 27 a is located on an inner peripheral side in the front housing 17. The first discharge chamber 29 a is formed into an annular shape and located on an outer peripheral side of the first suction chamber 27 a in the front housing 17.

A first front-side communication passage 18 a is formed in the front housing 17. The front end of the first front-side communication passage 18 a communicates with the first discharge chamber 29 a, and the rear end thereof opens at the rear end of the front housing 17.

The control mechanism 15 described above is provided in the rear housing 19. Also, a second suction chamber 27 b, a second discharge chamber 29 b, and a pressure regulation chamber 31 are formed in the rear housing 19. The pressure regulation chamber 31 is located in the central part of the rear housing 19. The second suction chamber 27 b is formed into an annular shape and located on an outer peripheral side of the pressure regulation chamber 31 in the rear housing 19. The second discharge chamber 29 b is also formed into an annular shape and located on an outer peripheral side of the second suction chamber 27 b in the rear housing 19.

A first rear-side communication passage 20 a is formed in the rear housing 19. The rear end of the first rear-side communication passage 20 a communicates with the second discharge chamber 29 b, and the front end thereof opens at the front end of the rear housing 19.

A swash plate chamber 33 is formed between the first cylinder block 21 and the second cylinder block 23. The swash plate chamber 33 is located at an approximate center in the front-rear direction of the housing 1.

Plural first cylinder bores 21 a are formed parallel to one another at equal angular intervals in a circumferential direction in the first cylinder block 21. Also, a first shaft hole 21 b is formed in the first cylinder block 21 to allow the drive shaft 3 to be inserted therethrough. A first sliding bearing 22 a is provided on the first shaft hole 21 b. A roller bearing may be provided instead of the first sliding bearing 22 a.

The first cylinder block 21 has a first recess 21 c, which communicates with the first shaft hole 21 b and is coaxial with the first shaft hole 21 b. The first recess 21 c communicates with the swash plate chamber 33 and forms part of the swash plate chamber 33. The first recess 21 c is shaped such that its diameter becomes smaller toward the front end in a stepwise manner. A first thrust bearing 35 a is provided on a front end of the first recess 21 c. A first connecting passage 37 a is formed in the first cylinder block 21 to allow the swash plate chamber 33 to communicate with the first suction chamber 27 a. Also, a first retainer groove 21 e is provided in the first cylinder block 21 to restrict a maximum opening degree of respective first suction reed valves 391 a described later.

A second front-side communication passage 18 b is formed in the first cylinder block 21. The front end of the second front-side communication passage 18 b opens at the front end of the first cylinder block 21, and the rear end thereof opens at the rear end of the first cylinder block 21.

Similarly to the first cylinder block 21, plural second cylinder bores 23 a are formed in the second cylinder block 23. The second cylinder bores 23 a are respectively paired with the first cylinder bores 21 a in the front-rear direction. The first cylinder bores 21 a and the second cylinder bores 23 a are equal in diameter.

Also, a second shaft hole 23 b is formed in the second cylinder block 23 to allow the drive shaft 3 to be inserted therethrough. The rear end of the second shaft hole 23 b communicates with the pressure regulation chamber 31. A second sliding bearing 22 b is provided on the second shaft hole 23 b. A roller bearing may be provided instead of the second sliding bearing 22 b.

The second cylinder block 23 has a second recess 23 c, which communicates with the second shaft hole 23 b and is coaxial with the second shaft hole 23 b. The second recess 23 c also communicates with the swash plate chamber 33 and forms part of the swash plate chamber 33. Accordingly, the front end of the second shaft hole 23 b communicates with the swash plate chamber 33. The second recess 23 c is shaped such that its diameter becomes smaller toward the rear end in a stepwise manner. A second thrust bearing 35 b is provided on the rear end of the second recess 23 c. A second connecting passage 37 b is formed in the second cylinder block 23 to allow the swash plate chamber 33 to communicate with the second suction chamber 27 b. Also, a second retainer groove 23 e is provided in the second cylinder block 23 to restrict a maximum opening degree of second suction reed valves 411 a described later.

The second cylinder block 23 includes an outlet port 230, a confluence discharge chamber 231, a third front-side communication passage 18 c, a second rear-side communication passage 20 b, and an inlet port 330. The outlet port 230 and the confluence discharge chamber 231 communicate with each other. Via the outlet port 230, the confluence discharge chamber 231 is connected to a condenser (not shown) making up a refrigeration circuit.

The front end of the third front-side communication passage 18 c opens to the front end of the second cylinder block 23, and the rear end thereof communicates with the confluence discharge chamber 231. The third front-side communication passage 18 c communicates with the rear end of the second front-side communication passage 18 b when the first cylinder block 21 and the second cylinder block 23 are joined together.

The front end of the second rear-side communication passage 20 b communicates with the confluence discharge chamber 231, and the rear end thereof opens to the rear end of the second cylinder block 23.

The inlet port 330 is formed in the second cylinder block 23. Via the inlet port 330, the swash plate chamber 33 is connected to an evaporator (not shown) making up the refrigeration circuit.

The first valve forming plate 39 is provided between the front housing 17 and the first cylinder block 21. Also, the second valve forming plate 41 is provided between the rear housing 19 and the second cylinder block 23.

The first valve forming plate 39 includes a first valve plate 390, a first suction valve plate 391, a first discharge valve plate 392, and a first retainer plate 393. First suction ports 390 a, the number of which is equal to the number of the first cylinder bores 21 a, are formed in the first valve plate 390, the first discharge valve plate 392, and the first retainer plate 393. First discharge ports 390 b, the number of which is equal to the number of the first cylinder bores 21 a, are formed in the first valve plate 390 and the first suction valve plate 391. A first suction communication hole 390 c is formed in the first valve plate 390, the first suction valve plate 391, the first discharge valve plate 392, and the first retainer plate 393. A first discharge communication hole 390 d is formed in the first valve plate 390 and the first suction valve plate 391.

The first cylinder bores 21 a communicate with the first suction chamber 27 a through the respective first suction ports 390 a. Also, the first cylinder bores 21 a communicate with the first discharge chamber 29 a through the respective first discharge ports 390 b. The first suction chamber 27 a communicates with the first connecting passages 37 a through the first suction communication hole 390 c. The first front-side communication passage 18 a communicates with the second front-side communication passage 18 b through the first discharge communication hole 390 d.

The first suction valve plate 391 is provided on the rear face of the first valve plate 390. The first suction valve plate 391 has the plural first suction reed valves 391 a which are capable of opening and closing the respective first suction ports 390 a by elastic deformation. The first discharge valve plate 392 is provided on the front face of the first valve plate 390. The first discharge valve plate 392 has plural first discharge reed valves 392 a which are capable of opening and closing the respective first discharge ports 390 b by elastic deformation. The first retainer plate 393 is provided on the front face of the first discharge valve plate 392. The first retainer plate 393 restricts a maximum opening degree of the respective first discharge reed valves 392 a.

The second valve forming plate 41 includes a second valve plate 410, a second suction valve plate 411, a second discharge valve plate 412, and a second retainer plate 413. Second suction ports 410 a, the number of which is equal to the number of the second cylinder bores 23 a, are formed in the second valve plate 410, the second discharge valve plate 412, and the second retainer plate 413. Second discharge ports 410 b, the number of which is equal to the number of the second cylinder bores 23 a, are formed in the second valve plate 410 and the second suction valve plate 411. A second suction communication hole 410 c is formed in the second valve plate 410, the second suction valve plate 411, the second discharge valve plate 412, and the second retainer plate 413. A second discharge communication hole 410 d is formed in the second valve plate 410 and the second suction valve plate 411.

The second cylinder bores 23 a communicate with the second suction chamber 27 b through the respective second suction ports 410 a. Also, the second cylinder bores 23 a communicate with the second discharge chamber 29 b through the respective second discharge ports 410 b. The second suction chamber 27 b communicates with the second connecting passages 37 b through the second suction communication hole 410 c. The first rear-side communication passage 20 a communicates with the second rear-side communication passage 20 b through the second discharge communication hole 410 d.

The second suction valve plate 411 is provided on the front face of the second valve plate 410. The second suction valve plate 411 is provided with the plural second suction reed valves 411 a which are capable of opening and closing the respective second suction ports 410 a by elastic deformation. Also, the second discharge valve plate 412 is provided on the rear face of the second valve plate 410. The second discharge valve plate 412 is provided with plural second discharge reed valves 412 a which are capable of opening and closing the respective second discharge ports 410 b by elastic deformation. The second retainer plate 413 is provided on the rear face of the second discharge valve plate 412. The second retainer plate 413 restricts a maximum opening degree of each of the second discharge reed valves 412 a.

In the compressor, a first discharge communication passage 18 is formed by the first front-side communication passage 18 a, the first discharge communication hole 390 d, the second front-side communication passage 18 b, and the third front-side communication passage 18 c. Also, a second discharge communication passage 20 is formed by the first rear-side communication passage 20 a, the second discharge communication hole 410 d, and the second rear-side communication passage 20 b.

Also, in the compressor, the first and second suction chambers 27 a and 27 b and the swash plate chamber 33 communicate with each other via the first and second connecting passages 37 a and 37 b and the first and second suction communication holes 390 c and 410 c. Consequently, the pressure in the first and second suction chambers 27 a and 27 b and the swash plate chamber 33 are substantially equal. Because a low-pressure refrigerant gas which has passed through an evaporator flows into the swash plate chamber 33 through the inlet port 330, the pressure in the swash plate chamber 33 and the first and second suction chambers 27 a and 27 b is lower than the pressure in the first and second discharge chambers 29 a and 29 b.

The drive shaft 3 is made up of a drive shaft body 30 extending along a drive axis O, a first support member 43 a, and a second support member 43 b. A first small-diameter portion 30 a is formed on the front end side of the drive shaft body 30, and a second small-diameter portion 30 b is formed on the rear end side of the drive shaft body 30. The drive shaft body 30 extends rearward from the front side of the housing 1 by being inserted rearward from the boss 17 a through the first and second sliding bearings 22 a and 22 b. Consequently, the drive shaft body 30 and thus the drive shaft 3 are supported by the housing 1 so as to be rotatable around [[a] ] the drive axis O. The front end of the drive shaft body 30 is located in the boss 17 a and the rear end thereof protrudes into the pressure regulation chamber 31.

The swash plate 5, the link mechanism 7, and the actuator 13 are provided on the drive shaft body 30. The swash plate 5, the link mechanism 7, and the actuator 13 are all disposed in the swash plate chamber 33.

The first support member 43 a is press-fitted to the first small-diameter portion 30 a of the drive shaft body 30 and located inside of the first sliding bearing 22 a in the first shaft hole 21 b. Also, the first support member 43 a includes a flange 430 configured to abut the first thrust bearing 35 a, and a mounting portion (not shown) configured to allow a second pin 47 b, which will be described later, to be inserted therethrough. A front end of a first return spring 44 a is fixed to the first support member 43 a. The first return spring 44 a extends from the first support member 43 a toward the swash plate chamber 33 along the drive axis O.

The second support member 43 b is press-fitted to the rear end of the second small-diameter portion 30 b of the drive shaft body 30, and is located in the second shaft hole 23 b. The second support member 43 b corresponds to a cap according to the present invention. A flange 431 is formed on the front end of the second support member 43 b. The flange 431 has a flat-shaped front face 431 a. The flange 431 protrudes into the second recess 23 c and abuts the second thrust bearing 35 b. Also, the rear end of the second support member 43 b protrudes into the pressure regulation chamber 31. In the second support member 43 b, a first slide member 432 and a second slide member 433 made of resin are provided in the rear of the flange 431. The first and second slide members 432 and 433 are in contact with and slidable along an inner circumferential surface of the second shaft hole 23 b.

The second sliding bearing 22 b is press-fitted into the rear end of the second shaft hole 23 b. Thereby, the second sliding bearing 22 b is provided in the second shaft hole 23 b.

The swash plate 5 has a flat annular shape and includes a front face 5 a and a rear face 5 b. The front face 5 a faces frontward of the compressor in the swash plate chamber 33. Also, the rear face 5 b faces rearward of the compressor in the swash plate chamber 33.

The swash plate 5 is fixed to a ring plate 45. The ring plate 45 has a flat annular shape with an insertion hole 45 a formed in the center. The swash plate 5 is attached to the drive shaft 3 by inserting the drive shaft body 30 through the insertion hole 45 a in the swash plate chamber 33.

The link mechanism 7 has a lug arm 49. In the swash plate chamber 33, the lug arm 49 is placed frontward relative to the swash plate 5 and located between the swash plate 5 and the first support member 43 a. The lug arm 49 is formed so as to be substantially L-shaped from the front end toward the rear end. As shown in FIG. 4, the lug arm 49 abuts the flange 430 of the first support member 43 a when the inclination angle of the swash plate 5 with respect to a direction perpendicular to the drive axis O becomes a minimum. A weight 49 a is formed at the rear end of the lug arm 49. The weight 49 a extends approximately half around a circumference of the actuator 13. The shape of the weight 49 a may be designed as appropriate.

As shown in FIG. 1, the rear end side of the lug arm 49 is connected to one end side of the ring plate 45 with a first pin 47 a. When the axis of the first pin 47 a is defined as a first pivot axis M1, the rear end side of the lug arm 49 is supported around the first pivot axis M1 so as to be pivotable with respect to the one end side of the ring plate 45, i.e., the swash plate 5. The first pivot axis M1 extends in a direction perpendicular to the drive axis O of the drive shaft 3.

The front end of the lug arm 49 is connected to the first support member 43 a via the second pin 47 b. When the axis of the second pin 47 b is defined as a second pivot axis M2, the front end of the lug arm 49 is supported around the second pivot axis M2 so as to be pivotable with respect to the first support member 43 a, i.e., the drive shaft 3. The second pivot axis M2 extends parallel to the first pivot axis M1. The link mechanism 7 according to the present invention is made up of the lug arm 49, the first and second pins 47 a and 47 b, and, in addition, first and second pulling arms 132 and 133 and a third pin 47 c, which will be described later.

The weight 49 a is provided so as to extend at the rear end of the lug arm 49, i.e., on the opposite side of the second pivot axis M2 with reference to the first pivot axis M1. As the lug arm 49 is supported by the ring plate 45 with the first pin 47 a, the weight 49 a passes through a groove 45 b in the ring plate 45 and reaches the rear face side of the ring plate 45, i.e., the side of the rear face 5 b of the swash plate 5. Therefore, a centrifugal force produced by rotation of the swash plate 5 around the drive axis O also acts on the weight 49 a at the side of the rear face 5 b of the swash plate 5.

In this compressor, the swash plate 5 is able to rotate together with the drive shaft 3 as the swash plate 5 is connected to the drive shaft 3 by the link mechanism 7. Also, the swash plate 5 is able to change its inclination angle due to the pivotal movement of both ends of the lug arm 49 around the first pivot axis M1 and the second pivot axis M2, respectively.

The pistons 9 each has a first head 9 a at its front end and a second head 9 b at its rear end. The first head 9 a is reciprocally accommodated in each of the first cylinder bores 21 a. The first head 9 a and the first valve forming plate 39 define a first compression chamber 21 d in each of the first cylinder bores 21 a. The second head 9 b is reciprocally accommodated in each of the second cylinder bores 23 a. The second head 9 b and the second valve forming plate 41 define a second compression chamber 23 d in each of the second cylinder bores 23 a.

An engaging portion 9 c is formed in the middle of each of the pistons 9. Hemispherical shoes 11 a and 11 b are provided in each of the engaging portions 9 c. The shoes 11 a and 11 b convert rotation of the swash plate 5 into reciprocating movement of the pistons 9. The shoes 11 a and 11 b correspond to a conversion mechanism according to the present invention. Thereby, the first and second heads 9 a, 9 b are able to reciprocate in the first and second cylinder bores 21 a, 23 a at a stroke corresponding to the inclination angle of the swash plate 5.

Here, in the compressor, when the stroke of the pistons 9 changes according to the change in the inclination angle of the swash plate 5, respective top dead center positions of the first heads 9 a and the second heads 9 b move. Specifically, as the inclination angle of the swash plate 5 decreases, the top dead center positions of the first and second heads 9 a and 9 b move such that the volume of the second compression chamber 23 d becomes larger than the volume of the first compression chamber 21 d.

As shown in FIG. 1, the actuator 13 is placed in the swash plate chamber 33. The actuator 13 is located rearward of the swash plate 5 in the swash plate chamber 33 and capable of advancing into the second recess 23 c. The actuator 13 includes a movable body 13 a, a partition body 13 b, and a control pressure chamber 13 c. The control pressure chamber 13 c is formed between the movable body 13 a and the partition body 13 b.

As shown in FIG. 3, the movable body 13 a includes a rear wall 130, a circumferential wall 131, a first pulling arm 132, and a second pulling arm 133. The rear wall 130 is located at a rear position in the movable body 13 a and extends radially in a direction away from the drive axis O. The rear wall 130 has an insertion hole 130 a through which the second small-diameter portion 30 b of the drive shaft body 30 is inserted. The circumferential wall 131 continues from an outer circumferential edge of the rear wall 130 and extends frontward in the movable body 13 a.

Both of the first pulling arm 132 and the second pulling arm 133 are formed at the front end of the circumferential wall 131. The first pulling arm 132 and second pulling arm 133 of the circumferential wall 131 are placed so as to face each other across the drive axis O and protrude frontward in the movable body 13 a. These first and second pulling arms 132 and 133 correspond to a coupling portion according to the present invention. A first pin hole 132 a and a second pin hole 133 a are bored through the first pulling arm 132 and the second pulling arm 133, respectively. The movable body 13 a is formed into a bottomed cylindrical shape by the rear wall 130, the circumferential wall 131, and the first and second pulling arms 132 and 133.

As shown in FIG. 1, the partition body 13 b is formed into a disk shape having a diameter that is substantially equal to the inside diameter of the movable body 13 a. A second return spring 44 b is provided between the partition body 13 b and the ring plate 45. Specifically, the rear end of the second return spring 44 b is fixed to the partition body 13 b and the front end of the second return spring 44 b is fixed to the opposite end side of the ring plate 45.

The second small-diameter portion 30 b of the drive shaft body 30 is inserted through the movable body 13 a and the partition body 13 b. The movable body 13 a is accommodated in the second recess 23 c and faces the link mechanism 7 across the swash plate 5. The partition body 13 b is placed in the movable body 13 a at a position rearward of the swash plate 5, and its periphery is surrounded by the circumferential wall 131. Consequently, the control pressure chamber 13 c is formed between the movable body 13 a and the partition body 13 b. The control pressure chamber 13 c is separated from the swash plate chamber 33 by the rear wall 130 and the circumferential wall 131 of the movable body 13 a and the partition body 13 b.

In the compressor, a required control pressure, which is the pressure in the control pressure chamber 13 c required to increase the inclination angle of the swash plate 5 to a maximum value, is preset to the control pressure chamber 13 c. The required control pressure is set lower than the upper limit of the discharge refrigerant pressure, i.e., the upper limit of the pressure of refrigerant gas in the first discharge chamber 29 a and the second discharge chamber 29 b.

In the compressor, due to the insertion of the second small-diameter portion 30 b, the movable body 13 a is able to rotate together with the drive shaft 3 and move along the drive axis O of the drive shaft 3 in the swash plate chamber 33. On the other hand, the partition body 13 b is fixed to the second small-diameter portion 30 b in the state that the second small-diameter portion 30 b has been inserted therethrough. The partition body 13 b is thus only able to rotate together with the drive shaft 3, and not able to move in the same manner as the movable body 13 a. As a result, the movable body 13 a moves along the drive axis O relative to the partition body 13 b. The partition body 13 b may be provided on the drive shaft body 30 so as to be movable along the drive axis O.

The first and second pulling arms 132 and 133 are connected with the opposite end side of the ring plate 45 by the third pin 47 c. The third pin 47 c extends from the first pin hole 132 a, which is shown in FIG. 3, to the second pin hole 133 a through the opposite end side of the ring plate 45. As shown in FIG. 1, when the axis of the third pin 47 c is defined as an action axis M3, the opposite end side of the ring plate 45, i.e., the swash plate 5 is supported by the movable body 13 a so as to be pivotable around the action axis M3. The action axis M3 extends parallel to the first and second pivot axes M1 and M2. The movable body 13 a is thus coupled to the swash plate 5.

The second small-diameter portion 30 b has an axial path 3 a, which extends frontward from the rear end along the drive axis O, and a radial path 3 b, which extends in a radial direction from the front end of the axial path 3 a and opens in an outer circumferential surface of the drive shaft body 30. The rear end of the axial path 3 a opens to the pressure regulation chamber 31. The radial path 3 b opens to the control pressure chamber 13 c. The control pressure chamber 13 c thus communicates with the pressure regulation chamber 31 through the radial path 3 b and the axial path 3 a.

A threaded portion 3 d is formed on a tip end of the drive shaft body 30. Via the threaded portion 3 d, the drive shaft 3 is connected to a pulley or an electro-magnetic clutch (not shown).

As shown in FIG. 2, the control mechanism 15 includes a low-pressure passage 15 a, a high-pressure passage 15 b, a control valve 15 c, an orifice 15 d, the axial path 3 a, and the radial path 3 b.

The low-pressure passage 15 a is connected to the pressure regulation chamber 31 and the second suction chamber 27 b. Through the low-pressure passage 15 a, the axial path 3 a, and the radial path 3 b, the control pressure chamber 13 c, the pressure regulation chamber 31, and the second suction chamber 27 b communicate with one another. The high-pressure passage 15 b is connected to the pressure regulation chamber 31 and the second discharge chamber 29 b. Through the high-pressure passage 15 b, the axial path 3 a, and the radial path 3 b, the control pressure chamber 13 c, the pressure regulation chamber 31, and the second discharge chamber 29 b communicate with one another. The orifice 15 d is provided in the high-pressure passage 15 b.

The control valve 15 c is provided on the low-pressure passage 15 a. The control valve 15 c is able to adjust an opening degree of the low-pressure passage 15 a based on the pressure in the second suction chamber 27 b.

In the compressor, the inlet port 330 shown in FIG. 1 is connected with a pipe leading to the evaporator while the outlet port 230 is connected with a pipe leading to the condenser. The condenser is connected to the evaporator through a pipe and an expansion valve. The compressor, the evaporator, the expansion valve, the condenser, etc. make up the refrigeration circuit of vehicle air-conditioning apparatus. Illustration of the evaporator, the expansion valve, the condenser, and the pipes is omitted.

In the compressor configured as described above, by rotation of the drive shaft 3, the swash plate 5 rotates and the pistons 9 reciprocate in the first and second cylinder bores 21 a and 23 a. Thereby, the first and second compression chambers 21 d and 23 d change their volumes according to the piston stroke. In the compressor, a suction phase for sucking refrigerant gas into the first and second compression chambers 21 d and 23 d, a compression phase for compressing the refrigerant gas in the first and second compression chambers 21 d and 23 d, and a discharge phase for discharging the compressed refrigerant gas into the first and second discharge chambers 29 a and 29 b take place repeatedly.

The refrigerant gas discharged into the first discharge chamber 29 a passes through the first discharge communication passage 18 and reaches the confluence discharge chamber 231. Similarly, the refrigerant gas discharged into the second discharge chamber 29 b passes through the second discharge communication passage 20 and reaches the confluence discharge chamber 231. After reaching the confluence discharge chamber 231, the refrigerant gas is discharged to the condenser through the outlet port 230.

While these suction phase and so forth take place, a piston compression force to reduce the inclination angle of the swash plate 5 is applied to a rotational body, which is made up of the swash plate 5, the ring plate 45, the lug arm 49, and the first pin 47 a. When the inclination angle of the swash plate 5 is changed, the stroke of the pistons 9 increases or decreases, and thereby, it is possible to control the displacement.

Specifically, when the control valve 15 c, which is shown in FIG. 2, of the control mechanism 15 increases the opening degree of the low-pressure passage 15 a, the pressure in the pressure regulation chamber 31, and thus the pressure in the control pressure chamber 13 c become substantially equal to the pressure in the second suction chamber 27 b. Due to the piston compression force acting on the swash plate 5, the movable body 13 a of actuator 13 moves frontward in the swash plate chamber 33 as shown in FIG. 4.

Consequently, in the compressor, the movable body 13 a pushes the swash plate 5 at the opposite end side frontward in the swash plate chamber 33 at the action axis M3 via the first and second pulling arms 132 and 133. Thus, in the compressor, the opposite end side of the ring plate 45, in other words, the opposite end side of the swash plate 5, pivots clockwise around the action axis M3 against a biasing force of the second return spring 44 b. Also, the rear end of the lug arm 49 pivots counterclockwise around the first pivot axis M1 and the front end of the lug arm 49 pivots counterclockwise around the second pivot axis M2. The lug arm 49 comes close to the flange 430 of the first support member 43 a. Thereby, the swash plate 5 pivots using the action axis M3 as a point of action and using the first pivot axis M1 as a fulcrum. This reduces the inclination angle of the swash plate 5 with respect to the direction perpendicular to the drive axis O of the drive shaft 3 and decreases the stroke of the pistons 9. Therefore, discharge capacity of the compressor per rotation of the drive shaft 3 decreases. The inclination angle of the swash plate 5 shown in FIG. 4 is the minimum value in this compressor.

Here, in this compressor, the centrifugal force acting on the weight 49 a is also applied to the swash plate 5. Thus, the swash plate 5 of this compressor is easily displaced toward a direction of reducing the inclination angle.

When the inclination angle of the swash plate 5 decreases, the ring plate 45 abuts the rear end of the first return spring 44 a. The first return spring 44 a thus deforms elastically and the rear end of the first return spring 44 a comes close to the first support member 43 a.

In this compressor, as the inclination angle of the swash plate 5 becomes smaller and the stroke of the pistons 9 decreases, the top dead center position of the second heads 9 b moves away from the second valve forming plate 41. Thus, in the compressor, when the inclination angle of the swash plate 5 approaches 0 degrees, compression work is performed slightly in the first compression chamber 21 d, whereas compression work is not performed in the second compression chamber 23 d.

When the control valve 15 c shown in FIG. 2 reduces the opening degree of the low-pressure passage 15 a, the pressure in the pressure regulation chamber 31 increases due to the pressure of the refrigerant gas in the second discharge chamber 29 b, and thereby the pressure in the control pressure chamber 13 c increases. Thus, the movable body 13 a of the actuator 13 moves in a rearward in the swash plate chamber 33, i.e., toward the flange 431 of the second support member 43 b, as shown in FIG. 1, against the piston compression force acting on the swash plate 5.

Consequently, in the compressor, the movable body 13 a pulls the opposite end side of the swash plate 5 rearward in the swash plate chamber 33 at the action axis M3 via the first and second pulling arms 132 and 133. Thus, in the compressor, the opposite end side of the swash plate 5 pivots counterclockwise around the action axis M3. Also, the rear side of the lug arm 49 pivots clockwise around the first pivot axis M1 and the front end of the lug arm 49 pivots clockwise around the second pivot axis M2. The lug arm 49 moves away from the flange 430 of the first support member 43 a. Thereby, the swash plate 5 pivots in a direction opposite to the above-described direction in the case of reducing the inclination angle, using the action axis M3 as a point of action and using the first pivot axis M1 as a fulcrum. This increases the inclination angle of the swash plate 5 with respect to the direction perpendicular to the drive axis O of the drive shaft 3.

Here, in the compressor, the movable body 13 a moves towards the flange 431 and pulls the opposite end side of the swash plate 5 rearward in the swash plate chamber 33 via the first and second pulling arms 132 and 133 until the pressure in the control pressure chamber 13 c reaches the required control pressure. Thus, the link mechanism 7 permits increase of the inclination angle of the swash plate 5 until it reaches the maximum value. The discharge capacity of the compressor per rotation of the drive shaft 3 increases as the stroke of the pistons 9 increases. When the pressure in the control pressure chamber 13 c reaches the required control pressure, the inclination angle of the swash plate 5 reaches the maximum value as shown in FIG. 1.

In the compressor, while the required control pressure of the control pressure chamber 13 c is set lower than the upper limit of the discharge refrigerant pressure as described above, the refrigerant gas is introduced into the control pressure chamber 13 c from the second discharge chamber 29 b through the high-pressure passage 15 b and the like. Therefore, in the compressor, even after the inclination angle of the swash plate 5 reaches the maximum value as described above, the pressure in the control pressure chamber 13 c continues to increase beyond the required control pressure.

In this regard, in the compressor, when the pressure in the control pressure chamber 13 c increases and reaches the required control pressure, the movable body 13 a moves rearward in the swash plate chamber 33 and the rear wall 130 abuts the front face 431 a of the flange 431. This allows the compressor to restrict the maximum value of the inclination angle of the swash plate 5. That is, in this compressor, although the movable body 13 a and the swash plate 5 are coupled to each other via the first and second pulling arms 132 and 133, for restricting the maximum value of the inclination angle, the swash plate 5 does not push the lug arm 49 of the link mechanism 7 due to the pressure in the control pressure chamber 13 c. In this compressor, the pressure in excess of the required control pressure acts on the flange 431 and thus on the second support member 43 b, but does not act on the swash plate 5 or the lug arm 49 of the link mechanism 7 via the first and second pulling arms 132 and 133. Therefore, it is not necessary in this compressor to ensure the strength of the swash plate 5 and the lug arm 49 more than required. Thus, the compressor eliminates the need to upsize the swash plate chamber 33.

In the compressor, the maximum value of the inclination angle is restricted by the rear wall 130 of the movable body 13 a and the flange 431 abutting each other, not by the link mechanism 7. Therefore, in the compressor, even if the swash plate 5 and the link mechanism 7 have dimensional tolerance and the like in the direction of the drive axis O, such tolerance does not cause dispersion in the maximum value of the inclination angle.

In the compressor, since the second support member 43 b is press-fitted to the drive shaft body 30, the second support member 43 b including the flange 431 rotates synchronously with the drive shaft body 30. Therefore, in the compressor, even when the rear wall 130 abuts the flange 431, the rotation of the movable body 13 a and even the swash plate 5 is not restricted by the flange 431.

Therefore, the compressor according to Embodiment 1, in which the inclination angle of the swash plate 5 is changed by the actuator 13, ensures excellent quality stability on a product-by-product basis while realizing reduction in size.

In particular, in this compressor, the maximum value of the inclination angle is restricted by having the flange 431 of the second support member 43 b abut the rear wall 130 of the movable body 13 a. Therefore, in this compressor, it is possible to adjust the position where the rear wall 130 abuts the flange 431 depending on the thickness of the flange 431 and the shape of the second support member 43 b by itself. Furthermore, in this compressor, it is also possible to adjust the position where the rear wall 130 abuts the flange 431 depending on the position where the second support member 43 b is press-fitted to the second small-diameter portion 30 b of the drive shaft body 30. Thus, the compressor is capable of suitably restricting the maximum value of the inclination angle.

Embodiment 2

In the compressor according to Embodiment 2, as shown in FIG. 5, a circlip 51 is fitted to the second small-diameter portion 30 b of the drive shaft body 30. More specifically, the circlip 51 is fitted to the second small-diameter portion 30 b at a position between the second support member 43 b and the movable body 13 a. Thereby, the circlip 51 is located in the second recess 23 c, i.e., in the swash plate chamber 33. The shape of the circlip 51 may be designed as appropriate. For ease of explanation, illustration of the pistons 9, the shoes 11 a and 11 b and the like are omitted in this figure. The other components of the compressor are the same as those of the compressor according to Embodiment 1, and, with respect to the same components, same reference numerals are used and detailed description thereof is omitted.

In this compressor, when the pressure in the control pressure chamber 13 c increases and reaches the required control pressure, the rear wall 130 of the movable body 13 a which has moved rearward in the swash plate chamber 33 abuts the circlip 51. This allows the compressor to restrict the maximum value of the inclination angle of the swash plate 5 without having the swash plate 5 push the link mechanism 7.

Also, in the compressor, it is possible to adjust the position at which the rear wall 130 abuts the circlip 51 depending on the position where the circlip 51 is press-fitted to the second small-diameter portion 30 b. Thus, the maximum value of the inclination angle can be suitably restricted in this compressor. The other operations of this compressor are the same as those of the compressor according to Embodiment 1.

Although present invention has been described above by referring to Embodiments 1 and 2, needless to say, the present invention is not limited to Embodiments 1 and 2 described above and may be modified and applied as appropriate without departing from the gist of the present invention.

For example, a protrusion may be provided on the rear wall 130 of the movable body 13 a exclusively for the purpose of abutting the flange 431 or the circlip 51. Also, the protrusion may be configured to be able to abut the second thrust bearing 35 b. In this case, the second thrust bearing 35 b corresponds to the maximum inclination restriction member according to the present invention.

Furthermore, the compressor may be configured as a variable displacement single head swash plate type compressor by forming cylinder bores only in either of the first cylinder block 21 and second the cylinder block 23.

Also, the control mechanism 15 may be configured such that the control valve 15 c is provided in the high-pressure passage 15 b while the orifice 15 d is provided in the low-pressure passage 15 a. In this case, it is possible to adjust the opening degree of the high-pressure passage 15 b using the control valve 15 c. Thereby, the pressure in the control pressure chamber 13 c can be increased quickly due to the pressure of refrigerant gas in the second discharge chamber 29 b, and the discharge capacity can be increased quickly.

INDUSTRIAL APPLICABILITY

The present invention is applicable to air-conditioning apparatus and the like.

REFERENCE SIGNS LIST

-   -   1 Housing     -   3 Drive shaft     -   5 Swash plate     -   7 Link mechanism     -   9 Piston     -   11 a, 11 b Shoe (conversion mechanism)     -   13 Actuator     -   13 a Movable body     -   13 b Partition body     -   13 c Control pressure chamber     -   15 Control mechanism     -   21 a First cylinder bore     -   21 d First compression chamber     -   23 a Second cylinder bore     -   23 d Second compression chamber     -   27 a First suction chamber     -   27 b Second suction chamber     -   29 a First discharge chamber     -   29 b Second discharge chamber     -   33 Swash elate chamber     -   43 b Second support member (maximum inclination restriction         member, cap)     -   51 Circlip (maximum inclination restriction member)     -   130 Rear wall (movable body)     -   131 Circumferential wall (movable body)     -   132 First pulling arm (coupling portion)     -   133 Second pulling arm (coupling portion)     -   O Drive axis 

1. A variable displacement swash plate type compressor comprising: a housing in which a suction chamber, a discharge chamber, a swash plate chamber, and a cylinder bore are formed; a drive shaft extending along a drive axis and rotatably supported in the housing; a swash plate rotatable in the swash plate chamber along with rotation of the drive shaft; a link mechanism that is provided between the drive shaft and the swash plate and permits change of an inclination angle of the swash plate in a direction perpendicular to the drive axis of the drive shaft; a piston reciprocally accommodated in the cylinder bore; a conversion mechanism that reciprocates the piston in the cylinder bore along with rotation of the swash plate at a stroke corresponding to the inclination angle; an actuator capable of changing the inclination angle; and a control mechanism that controls the actuator, wherein the suction chamber and the swash plate chamber communicate with each other, the actuator includes a partition body provided on the drive shaft, a movable body that is movable along the drive axis of the drive shaft in the swash plate chamber and provided with a coupling portion to be coupled to the swash plate, and a control pressure chamber that is defined by the partition body and the movable body and moves the movable body by introducing a refrigerant from the discharge chamber, and a maximum inclination restriction member that rotates synchronously with the drive shaft and restricts a maximum value of the inclination angle by abutting the movable body is provided on the drive shaft.
 2. The variable displacement swash plate type compressor according to claim 1, wherein: the drive shaft includes a drive shaft body and a cap that is press-fitted to the drive shaft body and located in the swash plate chamber; and the cap is the maximum inclination restriction member.
 3. The variable displacement swash plate type compressor according to claim 1, wherein: the compressor further comprises a circlip that is fitted to the drive shaft and located in the swash plate chamber; and the circlip is the maximum inclination restriction member. 